Graph.dart: A file can't be part of more than one library

[tbecker]

I upgraded to the new flutter version 3.22 and Dart SDK 3.4.4

For a previously working version, after the update

Error: A file can't be part of more than one library. (mentions first graph.dart, then others)
Try moving the shared declarations into the libraries, or into a new library.

Thanks for reviewing.